Question

Assertion (A) : Flocs are masses of bacteria associated with fungal filaments in secondary treatment of sewage.
Reason (R) : Flocs help in digestion of solid waste by aerobic respiration.

• A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
• B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
• C. Assertion (A) is true, but Reason (R) is false.
• D. Assertion (A) is false, but Reason (R) is true.

Hint:

Primary Treatment = Physical (Filtration/Sedimentation) of solid waste.
Secondary Treatment = Biological (Microbes/Flocs) of organic matter.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Secondary treatment of sewage is a biological process involving the use of microbes to reduce the organic load of wastewater.
Step 2: Detailed Explanation:
Assertion (A): During secondary treatment, the primary effluent is agitated in large aeration tanks. This allows vigorous growth of useful aerobic microbes into flocs. Flocs are indeed masses of bacteria associated with fungal filaments to form mesh-like structures. This statement is true.
Reason (R): While the microbes in flocs do perform aerobic respiration, they consume the organic matter (BOD) dissolved in the effluent. The term "solid waste" generally refers to the grit and debris removed during primary treatment (physical separation). Flocs do not digest the "solid waste" in the context of sewage treatment terminology; they digest dissolved or colloidal organic matter. Thus, the reason is technically false or inaccurate in its description.
Step 3: Final Answer:
Assertion is true, but the Reason is false regarding the digestion of "solid waste." Option (C) is correct.